Hybrid electric vehicles (HEVs) have a powertrain that includes an internal combustion engine (ICE) and an electric machine or electric motor generator/starter (M/G), which generate power and torque to propel the vehicle. HEVs also may include later generation transmissions that include various configurations enabling advanced operations and improved performance. Such engine, electric machine, and transmission components may implement one or more regenerative braking capabilities incorporating various controllers, components, and systems that enable optimized energy recovery during electric, frictional, and cooperative braking of HEV.